mw-gha-slack-notify

Cloudflare Worker that posts real-time GitHub Actions workflow status to Slack. Replaces action-slacksync — no more prepare/conclusion jobs or per-job action steps.

flowchart LR
  GH[GitHub Org Webhook] --> W[CF Worker]
  W --> DO[Durable Object]
  DO --> Slack[Slack API]
  DO --> DW[Dynamic Workers]
  W --> KV[KV Cache]

  DW -. custom renderers .-> DO
  KV -. config + tokens .-> W

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How it works

1. A GitHub App webhook fires workflow_run and workflow_job events
2. The Worker verifies the signature and routes to a Durable Object (one per org+env)
3. The DO posts a Slack message on the first event, then updates it as jobs progress
4. Custom renderer JS files (fetched from the repo) run in isolated Dynamic Workers

Usage

Add two env vars to any workflow to opt in:

env:
  SLACK_NOTIFY_CHANNEL: 'C012NUFBCLU'
  SLACK_NOTIFY_RENDERER: '.github/slack-notify.deploy.js' # optional

Without a renderer, a minimal default is used (job names, status colors, durations).

Custom renderers

Plain JS files — no Cloudflare deps required. Export a default function:

// .github/slack-notify.deploy.js

/** @type {import('@masterworks/mw-gha-slack-notify').Renderer} */
export default function render({ workflow_run, jobs }) {
  return {
    text: `${workflow_run.name} on ${workflow_run.repository.full_name}`,
    blocks: [
      { type: 'section', text: { type: 'mrkdwn', text: `> ${workflow_run.head_commit?.message}` } },
    ],
    attachments: jobs.map((job) => ({
      color: job.conclusion === 'success' ? '#2eb886' : '#a30200',
      text: job.name,
    })),
  }
}

For TypeScript, install the types package for RendererInput and RendererOutput:

pnpm add -D @masterworks/mw-gha-slack-notify@github:MasterworksIO/mw-gha-slack-notify

Setup

Prerequisites

• Cloudflare account with Workers, Durable Objects, and KV
• GitHub App installed on the org (permissions: contents:read, actions:read)
• Slack Bot Token with chat:write and chat:write.customize scopes

Secrets

wrangler secret put GITHUB_APP_ID
wrangler secret put GITHUB_PRIVATE_KEY    # PKCS#8 PEM
wrangler secret put GITHUB_WEBHOOK_SECRET
wrangler secret put SLACK_BOT_TOKEN       # xoxb-...

Deploy

pnpm install
pnpm -F mw-gha-slack-notify-worker deploy

Development

pnpm install
pnpm -F mw-gha-slack-notify-worker dev  # wrangler dev
pnpm typecheck                           # tsgo --noEmit (recursive)
pnpm test                                # vitest (recursive)
pnpm lint                                # oxlint
pnpm format                              # oxfmt

Project structure

packages/
  worker/     CF Worker: webhook handling, DO, Slack API, GitHub App auth
  types/      Slim types package: RendererInput, RendererOutput